1. Field of the Invention
The present invention generally relates to the field of battery chargers, and more particularly relates to the field of charging batteries within sealed portable electronic devices.
2. Description of the Prior Art
Rechargeable batteries are widely used in today""s electronic products. Many portable electronic devices use rechargeable batteries to avoid constant battery replacement. For certain low-power devices it is possible to construct an internal mechanism that relies on shaking or cranking or other motion to drive a small electric generator that charges a battery or capacitor. However, in most common situations, these mechanisms are too large, expensive or power-limited to be practicable.
Conventional connection techniques exist which employ electrical contacts or inductive or acoustic coupling. Solar photovoltaic cells have also been used to utilize solar power.
The following six (6) prior art references are found to be pertinent to the of art of the present invention:
1. U.S. Pat. No. 3,938,018 issued to Dahl on Feb. 10, 1976 for xe2x80x9cInduction Charging Systemxe2x80x9d (hereafter the xe2x80x9cDahl Patentxe2x80x9d);
2. U.S. Pat. No. 4,661,758 issued to Whittaker on Apr. 28, 1987 for xe2x80x9cSolar Power Supply And Battery Charging Circuitxe2x80x9d (hereafter the xe2x80x9cWhittaker Patentxe2x80x9d);
3. U.S. Pat. No. 4,808,904 issued to Ricaud et al. on Feb. 28, 1989 for xe2x80x9cPortable Photovoltaic Battery Rechargerxe2x80x9d (hereafter the xe2x80x9cRicaud Patentxe2x80x9d);
4. U.S. Pat. No. 5,451,765 issued to Gerber on Sep. 19, 1995 for xe2x80x9cEye Safety Protection System For A Laser Transmission System Wherein Laser Energy Scattered Back Along The Beam Path Is Detectedxe2x80x9d (hereafter the xe2x80x9cGerber Patentxe2x80x9d);
5. U.S. Pat. No. 6,275,325 B1 issued to Sinclair on Aug. 14, 2001 for xe2x80x9cThermally Activated Microelectromechanical Systems Actuatorxe2x80x9d (hereafter the xe2x80x9cSinclair Patentxe2x80x9d); and
6. U.S. Pat. No. 6,342,776 B1 issued to Taylor et al. on Jan. 29, 2002 for xe2x80x9cAcoustic Charger For Electronic Devicesxe2x80x9d (hereafter the xe2x80x9cTaylor Patentxe2x80x9d).
The Dahl Patent disclosed a normal 117-volt, 60-cycle source is converted into a high frequency signal resulting in radiation of a substantial portion of the energy in the signal. A receiving coil is inductively coupled to the radiation over a given distance substantially less than a wavelength of the high frequency signal to provide a received signal without the necessity of any electrical wires. The received signal in turn is converted into a D.C. signal and passed to a rechargeable battery for charging. The inductive coupling can be utilized for recharging portable electrical instruments having rechargeable batteries or for charging larger rechargeable batteries such as used in electrically driven vehicles.
The Whittaker Patent disclosed a photovoltaic power supply and battery charging system comprises a photovoltaic solar energy power supply panel connected through a blocking diode to a secondary storage battery which, in turn, is connected to a suitable load. A temperature sensitive reference voltage is supplied to one input of a voltage comparator, the other input to which is connected to the battery and thereby varies in accordance with the variations of charge on the battery. A short circuit shunt switch is connected directly across the photovoltaic panel; and this shunt switch is opened for varying periods of time by the output of a variable pulse width generator. The pulse width generator, in turn, is connected to and is controlled by the output of the voltage comparator to produce pulses of different widths. The charging current supplied to the battery then occurs in the form of high current pulses of varying widths depending upon the charge state of the battery.
The Ricaud Patent disclosed a portable photovoltaic battery recharger for simultaneously recharging a plurality of rechargeable batteries having different sizes and respective optimum charging current levels. The battery recharger includes a plurality of photovoltaic solar cells having a plurality of different selectively chosen surface areas for generating the respective optimum charging current levels when insulated, and battery receptacles for holding the plurality of rechargeable batteries in a recharging position. The plurality of solar cells are connected to the battery receptacles to transmit the charging current generated by each photovoltaic cell to respective ones of the plurality of battery receptacles such that batteries held in the battery receptacles are charged at respective optimum charging current levels.
The Gerber Patent disclosed an improved eye safety protection system for laser systems. The system measures energy returned along the optical axis itself. A beam splitter is installed in the optical axis and intercepts reflected energy back along the optical axis and passes the reflected energy to a photodetector which is used to measure the light scattered or reflected back along the emitting axis from the beam splitter. The output from the detector is passed to a comparator and regulation unit which adjusts the power level in the primary energy beam. Outgoing power can also be monitored.
The Sinclair Patent disclosed a microelectrical mechanical system (MEMS) actuator having coupled members that undergo different amounts of thermal expansion is disclosed for moving micromechanical objects, such as a mirror, toward and away from a surface or a planar substrate. The actuator members are a first elongate member at their respective distal ends. At their respective proximal ends, the members are mounted onto discrete electrical paths formed on the substrate. Thus, current applied to one electrical pathway is conducted along the first member to the second member, and to the other electrical path. The first member includes a metal conductor that provides a reduced resistivity for electrical current. Thus, when current is applied to the actuator, the second member generates more thermal energy due to its increased resistance and thereby thermally expands a greater amount than the first member, by thermally expanding the second member more than the first member, the distal ends of the first and second members are constrained to move away from the substrate. This movement is used to move a mirror out of the plane of the planar substrate. To accommodate the changing distance and angles between the actuator and the mirror, a sliding hinge is located between the actuator and the mirror.
The Taylor Patent disclosed a means for charging the battery of an electronic device by converting acoustic energy to electrical current. In one preferred embodiment, the protective layer of a liquid crystal display screen has a magnetic material disposed thereon. The housing of the liquid crystal display includes a corresponding coil of wire. As the protective layer has freedom of motion given by the liquid crystal panel, when acoustic energy is incident upon the protective layer, the protective layer moves, causing the magnetic material to generate a changing magnetic field in the coil. In an alternate embodiment, the protective layer is connected to piezoelectric transducers. When acoustic energy is incident upon the protective layer, the piezoelectric transducers are actuated. In another embodiment, the electronic device comprises an input for receiving concentrated acoustic energy from various sources including loudspeakers and acoustic waveguides.
While the above described prior art systems are related to battery charging devices, there are several limitations and drawbacks. For example, as the physical dimensions of the target devices shrink, or operation in harsh or wet environments is desired, physical contacts of the charging terminals become increasingly difficult to implement. Similarly, as the area available for a photovoltaic receptor diminishes, or the power requirements increase, solar charging becomes fatally limited by the solar constant.
In addition, inductive coupling limits the target appliance housing to nonconductive materials. Furthermore, acoustic coupling is generally impractical due to required sound levels.
Therefore, it is desirable to design and construct a new battery charging device that can recharge rechargeable batteries contained in a sealed housing in a target appliance or device.
The present invention is directed to a novel and unique optical battery charger for the recharging of batteries contained within a sealed housing in a target appliance. The target appliance can be any portable electronic device with modest power requirements.
The present invention optical battery recharger includes two main components. The portion internal to the target appliance includes one or more photovoltaic receptors and a charging circuit. The photovoltaic receptor(s) can be placed anywhere on the target appliance""s surface or, in some circumstances, within the target appliance behind a portion of the housing that is transparent to the operational wavelength. In some applications, data can also be transmitted over the charging link. A passive laser interlock mechanism is also described using a micro-mechanical reflector.
The external portion of the present invention optical battery recharger consists of an electrical power source, a focused solid-state light source such as a light emitting diode (LED) or a light amplification by stimulated emission of radiation (LASER) diode, and a physical cradle that aligns the target appliance""s receptor to the light source.
Further novel features and other objects of the present invention will become apparent from the following detailed description, discussion and the appended claims, taken in conjunction with the drawings.